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Non-controlling Interest (Tables) | 9 Months Ended
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Sep. 30, 2018
Noncontrolling Interest [Abstract] |
Non-controlling Interests | The following table presents the balance of non-controlling interests included in White Mountains’s total equity and the related percentage of each consolidated entity’s total equity owned by non-controlling shareholders as of September 30, 2018 and December 31, 2017:
|  | September 30, 2018 |  | December 31, 2017
$ in millions |  | Non-controlling Percentage |  | Non-controlling Equity |  | Non-controlling Percentage |  | Non-controlling Equity
Other, excluding mutuals |  |  |  |  |  |  |  |
HG Global |  | 3.1 | % |  | $ | 14.8 |  |  | 3.1 | % |  | $ | 15.9 |
NSM |  | 5.0 |  |  | 14.1 |  |  | — |  |  | — |
MediaAlpha |  | 37.8 |  |  | 15.3 |  |  | 35.7 |  |  | 13.1 |
Buzzmove |  | 22.9 |  |  | 1.5 |  |  | 22.9 |  |  | 2.5 |
Total other, excluding mutuals |  |  |  | 45.7 |  |  |  |  | 31.5 |
Mutuals |  |  |  |  |  |  |  |
BAM |  | 100.0 |  |  | (190.1 | ) |  | 100.0 |  |  | (163.2 | )
Total non-controlling interests |  |  |  |  | $ | (144.4 | ) |  |  |  | $ | (131.7 | )

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